Treatment of artificial materials



Patented Jan. 30, 1945 UNITED STATES PATENT OFFICE 2,368,154 TREATMENT or ARTIFICIAL MATERIALS of Delaware No Drawing. Application December 10, 1940, Se rial No. 369,404. In Great Britain January 11,

7 Claims.

This invention relates to the treatment of artificial materials, and particularly to the treatment of filamentary materials having a basis of an organic derivative of cellulose which have been stretched in a hot aqueous medium.

In British Patents Nos. 438,584, 438,585, 438,- 586, 438,587, 438,655 and 438,656 there are described methods by which cellulose derivative filamentary materials may be stretched in hot aqueous media, e. g., hot water or wet steam. Such treatments are generally found to reduce the extensibility of the materials, and processes have been described for restoring extensibility to the products, particularly treatments with shrinking agents, especially latent solvents according to the process of U. S. Patent No.'2',058,- 422. It has hitherto been supposed that a shrinkage of at least about 10% is necessary to restore extensibility to an extent of practical utility, preferably about 10-20%. We have now found, however, that by treating cellulose derivative filamentary materials which have been stretched in hot water or wet steam with dilute aqueous solutions of swelling agents for the cellulose derivative so that substantially no shrinkage occurs, there may be produced a good increase of extensibility with no substantial loss of tenacity. Products of the treatment are also found to possess an unusually high degree of resistance to wear and to creasing.

The swelling agents which may be employed according to the invention may be latent solvents or non-solvent swelling agents, e. g. ethylene glycol and ethyl alcohol, but, when treating materials having a basis of .cellulose derivatives which are soluble in organic solvents, it is preferable to employ true solvents.

Examples of such true solvents are dioxane,

acetone, formic acid, acetic acid, propionlc acid, 1

the monomethyi ether of ethylene glycol, and methyl ethyl ketone. If desired, two or more swelling agents may be employed in admixture in dilute aqueous solution to serve as the'treatment medium.

The concentration and temperature of the treatment medium are to a large extent interrelated, having regard to the critical feature that substantially no shrinkage may take place, and they will depend upon the nature of the filamentary materials to be treated, and the extent to which they have been stretched before treatment. with yarns of acetone-soluble-cellulose acetate which have been stretched in wet steam to 1.000% of their original length are, for example,

5 cess of 50-60 C.

Suitable treatment media for use 7-25% dioxane, 5-15% acetic acid and 5-30% acetone, all at 25 C.,'and 1-25% acetone at 4 50 C. (all percentages by volume). It is generally undesirable to employ temperatures in ex- With a view to reducing the tendency to shrink the materials which the dilute aqueous solutions may possess, there may be added to them a proportion of a salt, e. g., sodiumacetate or sodium 10 chloride. For example, a. proportion of l-5 or even up to 10% of sodium acetate may be incorporated in a dilute aqueous solution of acetic acid, and the resulting liquor employed as the treatment agent according to the invention.

.15 Such an agent is found to produce an increase in extensibility comparable with that produced by a similar agent without the sodium acetate,

to give a slightly improved tenacity and to havea reduced tendency to shrink the materials.

- While it is preferable to employ media which do not shrink the materials at all, substantial improvements in physical characteristics may be produced with media which produce a shrinkage up to 2% or even 4, 5 or 6%, e. g., a medium of 35-38 or 40% acetone at about 85 C. The time of treatment does not greatly a'flect the results, provided that the medium is allowed to remain in contact with the materials for a period of at least about 5 minutes. .Preferably the treatment is continued for 15 or minutes at least and it may last for a time upto 2 or more hours if desired.

It is important to ensure that the filamentary materials are substantially uniformly treated throughout their cross-section. This can be achieved, more particularly by strictly observing a minimum for the time'during which any particular medium is allowed to remain in contact with the materials. This mingnum mayreadily 40 be determined for any given set of conditions by noting the time at which change in extensibility substantially ceases.

, The present invention may, with advantage, be applied to-any cellulose derivative filamentary all materials which have been stretched in a hot aqueous medium, for example, to '200, 500, 1000 or 2000% or more of their original length. While cellulose acetate is the preferred cellulose derivative, materials having a basis of other cellulose derivatives may be treated, for example, materials having a basis of cellulose propionate, cel- I lulose butyrate, cellulose aceto-propionate, cellulose aceto-butyrate, ethyl cellulose, propyl cellulose, oxyethyl cellulose and oxyethyl cellulose 66 acetate, mixtures of cellulose derivatives with upper surface of a rotating each other or with other filament-forming materials, e. g., the linear superpolymers formed, for example, by self-condensation oi amino-carboxylic or amino-sulphonic acids or by condensation of diamines with dicarboxylic or disulphonic acids, and vinyl polymers. The invention may also advantageously be applied to cellulose derivative filamentary materials which, after lutions of swelling agents and/or higher tern-- peratures may be employed than in the case of materials which have not-been subjected to an esterifying operation. The treatment media according to the invention may be applied to the materialsfe. g. filaments, twisted or untwisted yarns and the like, in any desired manner as, for example, by, a bath treatment or by spraying or padding methods. For'treatment, the materials may-be loose, in the form of hanks, on bobbins or swiits, in the form of cakes produced by means of a centrifugal box, or in any other package form. The media may be applied to travelling materials, e. g., to yarns travelling from the stretching apparatus to a bobbin or other winding device, and removed therefrom after an appropriate time ing to a particularly valuable method of, applyingthe media totravelling materials, the mate rials are led round a rotating roller which is sprayed with the medium or in contact with the roller which dips into a bath of the medium so that, in efl'ect, the materials are contacted with a continuously renewed thin film of the medium without being immersed in a bath.

After treatment according to the invention the cellulose derivative materials may be subjected to further operations with a view to modifying their characteristics. In particular, cellulose ester materials may be saponifled to an appropriate extent, either wholly or partially, or homogeneously' or superficially. For example, the materials may be subjected to the action of dilute caustic soda solutions, e. g., of concentration 1% or less, the action of which may be moderated and/or rendered more uniform by the presence of salts such as, for example, sodium acetate.

There may thus be obtained yarns of higher tenacity and extensibility having a dyestuif afllnity comparable with that of cotton where saponiflcation has taken place to a greater degree or-an afllnity for cellulose derivative dyestufis where saponification has been carried out to a relatively low degree.

The following examples illustrate the invention:

Example 1' Hanks or low twist yarn, composed or dry-spun cellulose acetate filaments which have been stretched to times'theiroriginal length in wet steam to increase their tenacity, are immersed in a bath of aqueous acehme (percentage by volume) at-25 'C. for one hour. The hanks are Patent No. 489,436 and Y has elapsed. Accords crease-resistance, wane m tenacity is substantially maintained.

Example 2 substantially increased with no or no substantial loss of tenacity.

Although in both the preceding examples low twist yarn oi dry-spun cellulose acetate filaments is employed, it will be understood that analogous results may be produced by similar treatments or yarn having a higher twist or of dumb yarn, and of yarns of wet-spun as well as dry-spun cellulose acetate filaments. The degree of stretch does not affect the qualitative results, but only the degree of modification which is induced by the treatment.

Having described our invention, what we desire to secure by Letters Patent is:

1. A process for the improvement of the extensibility of artificial textile materials, which oomprises subjecting filamentary materials which have a basis of an organic derivative of cellulose, and which have been stretched in hot water or steam, to the action of a medium comprising an aqueous solution of a swelling agent for the cellulose derivative containing 1 to 30% of the swelling agent by volume, which medium at the temperature of the treatment has no tendency to shrink the materials, thetlme of contact of the filamentary materials with the medium being at least 5 minutes to ensure substantially uniform treated filamentary materials.

2. A process for the improvement 0! the extensibility of artificial textile materials, which comprises subjecting filamentary materials which have a .basis of an organic derivative of cellulose, and which have been stretched in hot water or steam, to the action 01' a medium comprising an aqueous solution of a true solvent for the cellulose derivative containing 1 to 30% of the solvent by volume, which medium at the temperature of the treatment has no tendency to shrink the materials, the time or contact of the filamentary materials with the medium being at least 5 minutes as ensure substantially uniform treatment of the filaments throughout their crossthenremovedtrbmthebatnwflsedwithwatel" anddried. 'lheyarnisi'oimdtopmlemallbstantiallyincreasedextensimityandwear-aud section, and the temperature 01' treatment being at most 60 C., and washing and drying said treated filamentary materials.

3. A process for the improvement otthe extensibility of artificial textile materials, which comprises subjecting filamentary materials which have a basis of an organic derivative oi. cellulose,

steam and which thereafter have been subjected toaneateriiyingoperatiomtotheactionota inncanprisinganlqueomsdutionoia swellingv agent for the eelllllm 'derivative com I with the medium being at least 5 minutes to ensure substantially uniform treatment of the filaments throughout their cross-section, and the temperature of treatment being at most 60 C., and washing and drying said treated filamentary materials.

4. A process for the improvement of the extensibility of artificial textile materials, which comprises su bjecting filamentary materials which have a basis of an organic derivative of cellulose, and which have been stretched in hot water or steam and which thereafter have been subjected to an esterifying operation, to the action of a medium comprising anaqueous solution of a true solvent for the cellulose derivative containing 1 to 30% of the solvent by volume, which medium at the temperature of the treatment has no tendency to shrink the materials, the time of contact of the filamentary materials with the medium being at least 5 minutes to ensure substantially uniform treatment of the filaments throughout their cross-section, and the tempergture of treatment being at most 60 C., and was ing and drying said treated filamentary materials.

5. A process for the improvement of the exten sibility of artificial textile materials, which comprises subjecting filamentary materials which at most 60' C., and washing and drying said treated filamentary materials.

6. A process for the improvement of the extensibility of artificial textile materials, which comprises subjecting fllamentary materials which have a basis of cellulose acetate, and which have been stretched in hot watern or steam and which thereafter have been subjected to an festerii'ying operation, to the action of a medium comprising an aqueous solution of a swelling agent for the cellulose acetate containing 1 to 30% of the-swelling agent by volume, which medium at the temperatureof the treatment has no tendency to shrink the materials, the time of contact of the filamentary materials with the medium being at least 5 minutes to ensure substantially uniform treatment of the filaments throughout their crosssection, and the temperature of treatment bein at most 60 C., and washing and drying said treated filamentary materials.

'7. A process for the improvement of the extensibility of artificial textile materials, which comprises subjecting filalmentary materials which have a basis of cellulose acetate, and which have have a basis of cellulose acetate, and which have been stretched in hot water or steam, to the action ot a medium comprising an aqueous solutlon of a swelling agent for the cellulose acetate containing 1 to 30% of the swelling agent by volume, which medium at the temperature of X the treatment has no tendency to shrink the materials, the time of contact of the filamentary materials with the medium being at least 5 minutes to ensure substantially uniform. treatment of the filaments throughout their crosssection, and the temperature of treatment being been stretched in hot water or steam, to the action of a mediuni'comprising an aqueous solution of acetonecontaining 5 to 30% of acetone Iby vol ume, which medium at the temperature of the treatment has no tendency to shrink the materials, the time of contact of the filamentar materials with the medium being at least 5 minutes to ensure substantiallyuniform treatment of the filaments throughout their cross-section, and the temperature 01' treatment being at most 60 C., and washing and drying said treated filamentary materials.

ROBERT WIGHTON.MONCR1EF 'F. HAROLD BATES. 

